This invention relates to a scroll compressor with a vent to protect a refrigerant system during a low charge situation.
Compressors are utilized to compress a refrigerant in a air conditioning, refrigeration or heat pump systems, in a refrigerant cycle, the refrigerant leaving the compressor typically passes to a condenser, and from the condenser to an expansion device. From the expansion device the refrigerant is passed to a evaporator, and then to the compressor. During this cycle through the system, a working fluid is cooled, as known.
At times, a refrigerant system may lose charge, or refrigerant mass, such as by leakage. When this happens, the liquid which typically passes through the expansion device could be a gas. When gas approaches the expansion device, the flow may be choked at the expansion device. This could result in significant reduction in the mass flow rate through the system.
The reduction of refrigerant flow causes the compressor to draw the suction side pressure to abnormally low levels. Abnormally low suction pressure levels can cause the compressor to see undesirably high pressure ratios. The combined effect of the high pressure ratios and the low mass flow rate will cause the compressor to run at abnormally high temperatures, which could damage the compressor.
Motors in the compressor are typically provided with a protection device which will shut the compressor motor down in the event of an unusually high temperature. However, by the time the motor senses this unusually high temperature through low charge as described above, damage could already have occurred in the compressor.
One type of compressor is a Scroll compressor. Scroll compressors are becoming widely utilized in refrigerant compression applications. A scroll compressor consists of a first scroll member having a base and a generally spiral wrap extending from the base. This first scroll member has its wrap interfitting with the wrap of the second scroll member to define compression chambers. The first scroll member is driven to orbit relative to the second scroll member, and entrapped fluid in the chambers is compressed to compress an entrapped fluid.